The present invention relates to a thrust reverser for a turbofan-type turbojet engine, more particularly such a thrust reverser having a rear support frame to which the thrust reverser actuator is attached.
Turbojet engines of the turbofan-type are well known in the art and typically comprise a primary exhaust gas duct to exhaust the high temperature gases and a secondary duct concentrically located about the primary gas exhaust duct so as to define an annular space therebetween. Turbofans, typically mounted on the front of the engine, direct air through this annular space to increase the performance characteristics of the engine.
In such turbofan engines, particularly those having a high bypass ratio, it is known to provide a thrust reverser which acts primarily or solely on the cold air passing through the secondary duct. A typical thrust reverser structure is illustrated in FIGS. 1 and 2 and comprises an upstream structure 101, a moveable thrust reverser element 102 and a downstream or rear collar 103 which is attached to the upstream structure 101. The stationary upstream structure 101 comprises an outer panel 104 which defines an outer flow surface and an inner panel 105 which defines an inner flow surface and which bounds the outer portion of the cold flow secondary duct. These panels are interconnected by a generally annular frame 106 which extends about the longitudinal axis L.
The frame 106 also is attached to the thrust reverser actuator 107a which has an extendible and retractable piston rod attached to a pivotable thrust reverser door 107 so as to move the door between its forward thrust position, illustrated in FIG. 1, and its reverse thrust position, illustrated in FIG. 2. The number of movable thrust reverser doors 107 will, of course, vary according to the particular application of the turbojet engine, and typically comprises 2, 3 or 4 such doors 107.
The thrust reverser door 107 also comprises an outer door panel 109 which, in the forward thrust position, is generally flush with the outer panel 104 and the outer surface of rear collar 103 so as to provide a smooth surface for the flow of air, indicated by arrow 110. Door 107 also has inner panel 111 and structure 112 which interconnects the outer and inner door panels 109 and 111, along with upstream baffle 113. The inner door panel 111 is located obliquely to the line 114 interconnecting the inner panel 105 and the inner surface of the rear collar 103 so as to define space 116 along with deflection edge 108. The air flow through the secondary duct is indicated by arrow 115 and passes from an upstream direction (towards the left as illustrated in FIG. 1) towards a downstream direction (towards the right as illustrated in FIG. 1).
FIG. 2 partially illustrates the turbofan duct with the thrust reverser doors 107 in their open or reversed thrust positions. The movement of the doors 107 between their open and closed positions is achieved by actuating cylinders 107a which have an extendible and retractable piston rod connected to the thrust reverser door 107 and the actuating cylinder attached to the support 106, located upstream of the reverse thrust opening.
Examples of known thrust reversers can be found in French patents 2,618,853; 2,618,852; 2,621,082; 2,627,807; 2,634,251; 2,638,207; and 2,651,021.
In all of these known thrust reversers, the upstream frame 106 is connected to the rear collar 103 via beams 9a. Since the frame 106 also supports the actuators 107a, it must absorb all of the mechanical stresses due to the structure's mass and inertia, as well as aerodynamic stresses imparted on the engine itself. This requires the front frame 106 to have increased strength which, inherently, increases the weight of the support and aircraft engine.